Previously, according to a method for adding liquid detergent (or softening agent, sanitizer, etc.) into electric washing devices such as clothes washing machine and dish washing machines, which use liquid detergent, users store the liquid detergent to be put into a designated container and washing devices put the detergent into barrels in a flushing or other mechanical ways by the washing process. In this way, the volume of the detergent released is determined by the operation of the users randomly, and the detergent needs releasing into the container each time when washing proceeds. As the detergent is continuously liquidized, storage of much detergent in a washing device is an application trend. In this way, the user can put into a certain amount of detergent upon demands in the washing process, thus simplifying the operation of the user and also performing automatic adjustment to the volume of the detergent released according to the category and quantity of the washed substances. Therefore, configuring an automatic detergent release on the washing machine is a development direction.
According to the prior art, there are following examples. In Japanese Patent Laid-Open 61-172594, for liquid detergent filled in a container, a certain pressure is released through an air pump to control the opening time of valve, thus controlling the volume of the detergent released. In Japanese Patent Laid-Open 2000-334197, an air pressure is completely released to the liquid detergent in the container to push the detergent out of the container. Those solutions need the user to completely seal the tank cover after the liquid detergent tank is fully filled within the detergent. If the sealing is poor, the pressure of the pump will leak. Even if the pressure of the pump is the same, the liquid detergent with different viscosity flows at a speed rate under the same pressure, thus causing inaccurate volume. In addition, the noises of the pump also affect the noise indicator control of the washing devices.
According to a technical solution disclosed on the Chinese market, a liquid detergent tank is disposed at the bottom of a washing device, through the pressure generated by a gear pump, and the liquid detergent is pressed to or attracted to a water box on the top of the washing device and then delivered into the barrel. In this solution, the gear pump is usually submerged in the detergent. When the detergent is exhausted, the residual detergent in the pump gets dry and solidified. During re-use, a big damping force will be generated to block the gear in the gear pump from rotating. And, the working noises of the gear pump do not affect the control over the noises indicators of the washing device. Moreover, this solution also has the problem that the difference in application speed caused by the fluctuation of the detergent viscosity causes application error.
In conclusion, if all the above-disclosed technologies employ the air pump to provide power, the problem of inaccurate volume of the detergent released due to the leakage from seal of the detergent tank cover and changes in the viscosity of the liquid detergent will be generated. When the contact mode similar to the gear pump is employed to provide the detergent with flowing force, the problem that the solidification of the liquid detergent causes blockage of the pump.
A Japanese Patent Laid-Open 11-019391 provides a solution, in which a water pump is disposed in the clothes washing machine; the water pump absorbs the water in the barrel of the washing machine and the water in the bathing pool; the water flows through a nozzle disposed on the pipe in the barrel; the nozzle has a negative pressure generator; when the pump delivers the water, the detergent is absorbed into the main water flow by means of the negative pressure generated by the nozzle, mixed and then put into the barrel. The power generated by means of this technology avoids the sealing problem of the power solution of the air pump and the solidification problem of the residual detergent of the gear pump solution, but the premise of this solution is to provide a water pump that provides a constant pressure. In this way, the cost is very high.
CN201258409Y discloses a device for generating the negative pressure in virtue of the water flow, but the negative pressure is generated by the tap water flow, but the force of the negative pressure is greatly related to the tap water pressure and the flow, so when the incoming water of the electromagnetic valve in the washing device is directly used to generate the negative pressure, the negative pressure will fluctuate in a large scope, and it is difficult to control the accuracy of the volume of the detergent.
Embodiment 2 of CN201258409Y puts forward that a metering box is disposed between the negative pressure device and the detergent box. Close valve 1-1 and valve 1-2, open valve 1-3 and valve 1-4, and then the metering box generates vacuum inside. Next, close valve 1-3 and valve 1-4, open valve 1-2, and then the liquid detergent flows into the metering box by means of the residual vacuum in the metering space. Then, close valve 1-1 and open valves 1-2, 1-3 and 1-4, the detergent in the metering box is absorbed into the water box through the negative pressure generated by the water flow.
CN201258409Y put forwards the method for solving the problem of volume error of the detergent resulted from the fluctuation of the negative pressure caused by the water flow in embodiment 1. However, in this solution, the metering box filled with the detergent absorbs the detergent through the negative pressure resided in the metering box on condition that the negative pressure source is cut from the metering box space. When the negative pressure is insufficient, the metering space cannot be fully filled, thus resulting in low accuracy of detergent volume. Actually, when the metering box and the negative pressure source are connected, the metering box never reaches the so-called vacuum. Let alone that when the metering box is cut from the vacuum source, the metering box has a certain negative pressure, but still has a certain air pressure (a certain amount of air exists), and as the metering box is filled with the liquid detergent, the residual space of the metering box gets small while the certain amount of air is compressed; then, the negative pressure in the residual space of the metering box disappears, and in such circumstances, the metering box cannot be filled with the detergent any more. With poor sealing of the metering box, this is a big problem. In addition, the detergent filled in the metering box is absorbed into the main water flow in virtue of the negative pressure. The detergent resides from the valve to the pipe. The concentrated or solidified detergent will block the flow of the detergent, and finally may affect the release effect.